It is with heavy hearts that we share the news that Suni, one of the last northern white rhinos in the world, was found dead in his boma (hut) on Friday at Ol Pejeta Conservancy, in Kenya’s Laikipia region.

According to a statement from Ol Pejeta, it is thought that he passed away from natural causes, although the Kenya Wildlife Service veterinarians have not yet conducted their post mortem examination. They did confirm that he was not killed by poachers. Suni was 34, and his father died of natural causes at the same age eight years ago.

With Suni’s death there are now only six northern white rhinos remaining in conservancies. He was one of the last two breeding males left–and only two breeding females remain–which makes the endangered species even more vulnerable to extinction.

But the conservancy won’t give up without a fight: “We will continue to do what we can to work with the remaining three animals on Ol Pejeta in the hope that our efforts will one day result in the successful birth of a northern white rhino calf.”